1. Field of the Invention
Embodiments of the present invention generally relate to surveillance systems and, more particularly, relates to a method and apparatus for dynamically configuring sensor placement using a 3D model.
2. Description of the Related Art
The current preferred method for optimizing the design of a sensor (e.g., a camera) layout is to begin with a 2D plan view of the environment, and to place cameras manually on the 2D plan view. In many cases, the design finishes at this point. In other cases, the desired field of views of the cameras are computed using a spreadsheet that computes the pixel size of an object given a camera's field of view using a 2D model of the environment. The cameras are then positioned at the computed distance apart (from one another) in an attempt to make sure that objects in the camera view are the correct size, and that all of the desired portions of the scene are covered by a camera view.
One problem with this approach is that the 2D model does not accurately capture the complex 3D projection of the scene into the 2D imager. For example, a camera looking obliquely at the scene will cover a different portion of area on the ground compared to a camera looking less obliquely. This significantly changes the area of coverage, and makes it difficult to guarantee that an area of ground will in fact be covered when the cameras are actually installed.
Another problem associated with this approach is that regions of occlusion are typically missed, resulting in unexpected blind-spots in camera coverage that are only apparent when the cameras are installed. It is often too expensive to fix the problem by adding or re-positioning cameras in a trial and error approach.
Another approach to designing a camera layout is to visit the location, and to gain access to each candidate site for a camera. A user holds up a calibrated, rectangular device and the scene is observed through the rectangle. The size of the rectangle is varied to simulate variation in the field of view of the camera. However, this approach requires the user to visit the location and repeat the process of calibrating the rectangular device for each camera location. This approach is expensive and impractical in many locations.
With each of the above-described approaches a user is unable to ascertain an accurate indication of the sensor coverage of a desired site until all of the sensors are installed and evaluated. Therefore, there is a need in the art for a method and apparatus for dynamically providing sensor and/or camera placement using a 3D model.